| Author | Message | ||||
     Christopher Williams Unregistered guest |
Hello all, I am needing the refrigerant charge weight for my 1989 Bentley Mulsanne S, with the Sanden compressor. In my searches, I have found numbers that range from 2.2lb, to 4.5lb. I attempted to look this up in the manual that is posted on the RROC.ORG.AU homepage, but the information I need is Chapter C, section C5, and the online manual stops at C4. It would be great for others if that could be corrected also. Thank you for any assistance, Chris Williams (Message approved by david_gore) | ||||
| Brian Vogel Grand Master Username: guyslp Post Number: 1883 Registered: 6-2009 |
See the attached taken from IETIS for the 1990-2000 model years, but covers the earlier model years.
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| Christopher Williams Unregistered guest |
Thank you for the chart, Brian. Just so I clarify, as the way the chart is broken up with lines is slightly confusing, I read this chart as stating my particular car would require 4lb, 4oz of refrigerant, as it is prior to 1994, not a Touring limo, and has the Sanden compressor. Am I reading this correctly? Chris Williams (Message approved by david_gore) | ||||
| Christopher Williams Unregistered guest |
As an update, the refrigerant amount listed in the chart is not correct for my particular car. I charged it to this amount and the high/low side pressures were more than double what they should have been for the ambient temps, and as a result, no cooling at the vent. Does anyone know the correct amount by weight, or even better, can the technical library where this information should be, please be completed? Thank you, Chris Williams (Message approved by david_gore) | ||||
| David Gore Moderator Username: david_gore Post Number: 2043 Registered: 4-2003 |
Chris, The content in the Technical Library is limited to what information our contributors can provide. If it is not there, we do not have it and accordingly request if anyone has this information for them to either post it on the Forum or send it to me as message through the Forum and I will pass it on to the Library supervisors | ||||
| michael vass Prolific User Username: mikebentleyturbo2 Post Number: 164 Registered: 7-2015 |
Hi Chris The sticker on my sanden 150 says 1.93 Kgs but that would be for R12 so I'm lead to think it should be 85% of that for R134a which I guess your using. So that would be about 3.6 lbs ,does that sound better to you? Hope that helps Mike | ||||
| Omar M. Shams Grand Master Username: omar Post Number: 629 Registered: 4-2009 |
Dear Chris, I don't use the weight method to get the right amount of gas into my car. Assuming that the system is vacunmed properly and that there is zero moisture as a result of a thorough vacuuming, and there is the right amount of oil in the system, I fill up with R134a until i can just see the bubbles disappearing in the sight glass on the receiver drier. That is then the optimum amount of gas. | ||||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1527 Registered: 6-2006 |
Here is something that I've not seen anywhere else . . . Another thing to look out for. If your pipes have the "pre gassed" type quick fit adaptors on them - I have found that these can cause restrictions in the wrong places and mess your pressures up. If you undo where the air con pipes look like they have extra nuts or adaptors in line you will probably find that there are brass valves inside. Remove all the inside parts so that you have a clear flow. They are fitted to allow the different sections of the air con system to be fitted to the vehicle or engine at the factory without being connected up but so no moisture can get in. When the connections are screwed together both valves open. Unfortunately over the years the seals expand and the brass gets coated in crud restricting the flow. A good test is feel both sides of the joints and if is cooler on the outlet side, it is acting as an expansion valve or orifice. I remove them if there are problems or if a system is empty for any reason. Omar - yes, sight glasses are great  If converting from R12 To 134a you will still have some bubbles though, don't over fill. | ||||
| Brian Vogel Grand Master Username: guyslp Post Number: 1897 Registered: 6-2009 |
Christopher, Not that I doubt you regarding the figure being incorrect, but that chart comes directly out of IETIS for the 1990-2000 model year cars and, as you can see, has information for some aspects of earlier models at times. Crewe's documentation is not without errata, and this is one of those places. I, like you, also found the layout of this chart to be really bizarre. It's been a long time since I last did AC charging myself, but back then (which was the R12 era) I followed something similar to the technique Omar describes, as well as checking out what was happening as far as the temperature drop and actual temperature of the air coming out of the vents. These "by weight" figures really don't mean all that much if you're doing temperature checking and sight glass checking as part of the fill process. My experience with R12 was even that you'd have (or at least could have) some bubbles at the receiver dryer as the compressor cycles and still have cooling that was perfectly within functional limits. The visual was a guideline while the temperature measurement was "the gold standard." Brian, who's still got R12 in LRK37110 and in my daily driver, the 1989 Sedan de Ville | ||||
| Omar M. Shams Grand Master Username: omar Post Number: 633 Registered: 4-2009 |
Dear Paul, You are right about the difference in bubble levels for R12 and R134a. No bubbles for R12 and a small number of bubbles for R134a gives optimal performance. The point you make about these in line crappy things is so so so important in hot climates. Any car I buy I make sure I delete these widgets on the first dis assembly of the system. | ||||
| michael vass Prolific User Username: mikebentleyturbo2 Post Number: 166 Registered: 7-2015 |
Hi Paul and Omar where exactly in the pipework are these 'widgets'? I will take them out before I gass mine. Cheers Mike | ||||
| Brian Vogel Grand Master Username: guyslp Post Number: 1898 Registered: 6-2009 |
Hello All, I think I've stumbled upon the answer regarding the R134a charge weight in later SZ cars with the Sanden compressor. Why this isn't noted elsewhere in IETIS I do not know. Why the discussion of R12 in the context of the VINs noted is a mystery to me. Perhaps this is one of those delivery market things, but by the time the 30K series hit US shores I am all but certain that R12 was already gone and R134a was legally mandated. Regardless of which refrigerant, the figure quoted is about half or less of those in the prior chart I posted. If anyone's got hard data regarding which refrigerants were used in which delivery markets during "the transition period" that would be really helpful information to have out there. Brian
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| Brian Vogel Grand Master Username: guyslp Post Number: 1899 Registered: 6-2009 |
And another set of additional documents related to earlier cars converted from R12 to R134a, but presumably retaining their original compressors. The documentation on that states that the refrigerant charge weight is reduced 15% from the figures quoted for R12 but that the oil amount remains the same (even though the type changes). Brian
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| Christopher Williams Unregistered guest |
Very interesting find, Brian. I will be tearing my system apart yet again this weekend as the new compressor I installed has a loud howl from the from the front bearing at 1500 RPM. I charged to 2.5lb as a starting point, and actually had a 45F vent temp on an 80F day, high/low pressures were 190/29psi, so I think I may just run with it. My car is earlier than the service bulletin you found, it does however have the Sanden compressor, but the remainder of the system is very similar to the previous models that used the A6. This car does not have a sight glass any longer as the drier has been replaced, and no longer has it. I tended to never trust sight glasses personally, as it was very easy to overcharge with them using R12, and almost impossible to use for R134a. Also, as an aside, I do service a 1991 30,000 series Silver Spur II that was sold new in Texas, and it was originally an R12 equipped car, and still retains it, and works fantastic. If I remember correctly, the change was mandated for the 1995 model year, although several manufacturers started the process earlier. (Message approved by david_gore) |
Refrigerant and Oil Requirements for SZ Cars